1. Field of the Invention
This invention relates to pad-mounted switchgear for high voltage underground distribution systems, and particularly to switchgear units of the type provided with a motor operator which may be actuated remotely or at the pad side to open and close the switch blade contacts.
An improved, inexpensive and highly reliable connector is provided for coupling and decoupling the motor operator from the rotatable switch blade supporting shaft to facilitate selective opening of the blade contacts or for exercising or performing maintenance on the motor operator. The connector includes a manually manipulable control member which is adapted to be actuated to couple or decouple the motor operator from the blade supportive shaft without the necessity of using tools or the like.
2. Description of the Prior Art
Underground electrical transmission and distribution systems include a main service line leading from a substation with a number of individual distribution lines connected in parallel to the main line at strategic points along the length of the latter. It is often the practice, particularly where power is supplied to a user entity such as a manufacturing facility, office building, shopping center or discrete residential development to provide padmounted switchgear in each of the lateral distribution lines connected to the main in order to allow selective de-energization of that lateral distribution line without the necessity of de-energizing all of the latter distribution lines because of opening the service main. Switchgear apparatus conventionally includes movable contacts which may be opened and closed by maintenance personnel, as well as fuse structure which protects the line from the influence of high or low level faults that may occur in one of the branch laterals. In particularly useful types of switchgear, vacuum or oil switches are employed for circuit control along with the fusing structure to minimize the overall size of the switchgear housing.
Generally, the vacuum switch contacts of padmounted switchgear as described require a snap action opening and closing mechanism to minimize arcing and assure a positive closing of the switch contacts. Actuation of the switch operating mechanism is normally accomplished by hand. In some cases, however, motor operators have been installed on the switchgear cabinet for powered actuation of the switch blade opening and closing mechanism. Recently, there has been increased interest in a switch contact actuating mechanism that is motor operated and can be activated at remote locations, as well as locally by a switch within the cabinet.
An improved motor operator for padmount switchgear is shown and described in U.S. Pat. No. 4,804,809 to Thompson et al., and is incorporated herein by reference. The motor operator connector thereof permits manual actuation in the event of motor failure or in the event the operator desires to open the switch contacts by hand. However, the motor operator thereof is somewhat expensive to construct and required a separate wrench to remove the drive element to permit manual actuation. A need has thus been perceived for a motor operator which has a simpler construction for coupling the actuator to the shaft and which allows quick and easy operative coupling and decoupling of the actuator and the shaft without the need for tools.